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Oil leak mystery


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I am writing to you, because my shop has no idea where elso to look for the source of this oil leak. I am flying a 66 M20E with IO360-A1A. Since a couple of weeks I do have eingine oil on my front tire after every flight. My shop cleaned the engine now 3 times, exchanged a gasked of one push-rod tube and a fitting of an oil return line, but still I do have these drops after every flight right on the tire ( see picture). The breather vent and tube are ok, and showing the standard 2-3 drops after shutdown. Does anybody have a similar experience? Otherwise this leak will destroy our annual flying holidays, which we are really looking forward to. 1b1b1c484eec6608de55b9ff3e688a10.jpg

 

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Is that coming out of the wheel well or the cowl?  If the wheel well, it is getting behind the close out panel on the firewall.  I would take a close look at the prop governor.  It is under high pressure and a little leak will look bad.  There is a small shelf on the firewall just behind the governor where oil may accumulate...check there first.

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Suffice to say, that's not normal and you need to get to the bottom of this before your holiday!

I had a similar issue recently and the oil amount and drip pattern (this is like blood spray analysis in a crime scene) that was similar to yours. Follow Clarence @M20Docadvice, me and my A&P washed the engine and ran it for few minutes with cowls removed then look for the leak. Turns out the  lower cooling baffle is slowly cutting the rocker box drain line (there is a Mooney SI on this but I am not sure if it applies to your engine)! Send a chill up my spine realizing that I had been flying with this problem. Even more troubling was that initially I was going to ignore it because I had a governor oil leak after O/H and a filter, I thought it could be the combination of the two. It's only a 1.5 hour fix

So don't ignore it!

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Lets see,  I have had drips from leaking mag seals, push rod seals, oil returns on the bottom of engine and even a couple from loose or missing case bolts.  The best way to determine the source is to remove cowls, clean engine, add dye, run and look for leaks. It is pretty difficult to find a leak by just looking because the oil gets blown all over the place.

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+1 for all the various rubber bits and seals that can possibly result in a leak...

+1 on the fluorescent dyes that can be added to the oil to aid in finding where the leak is coming from...

The other leak source can be the engine block.  The fine seal between the block halves sometimes causes dissapointment.  Another oddity is a crack in the case up by one of the cylinder bosses....

You are almost there.  Keep looking for it until you find it.

Welcome aboard.

What's the red marker on the nose wheel for?  

When you get a chance, add some data to your avatar...  :)

Best regards,

-a-

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Bubblehead 10-22-2016 12:21 PM

Dual Mag engines and prop governor oil leak safety issue
 
I have been researching oil leaks because I have been fighting one on my engine for a couple of months. I came across several accident reports for airplanes with "D" suffix engines that experienced loss of power, sometimes engine overspeed, and often complete destruction of the engine due to loss of oil between the prop governor and the governor mounting pad. This pertains to rear mounted governors.

My engine is a O-360-A1F6D converted to fuel injection so this concerned me. The problem arises because engines with dual magnetos need a spacer plate with gaskets on each side on the prop governor or the governor shaft will bottom out and hold the governor out just enough to allow for an oil leak. Sometimes minor, sometimes catastrophic.

If you have a dual mag engine make sure you have this plate and the 2 correct gaskets installed.

Confusion happens over the right installation parts because Hartzell's instructions don't show it, they only say these are general instructions and check your airframe and powerplant manuals. Cessna's orginal manuals for the Cardinal RG, where my engine came from, don't show the spacer plate but Cessna put out an update that has apparently not been noticed by a lot of A&P/AIs. The Lycoming parts manual for my engine does show the plate but does not show the governor in the same illustration so it does not tell you to add the second gasket. That is why 1438A (below) is so important. In 1438A it shows the plate and two-gasket arrangement but with the close off plate not the governor. The 2nd gasket in that diagram has to be replaced with a MS9144-01 gasket. The Hartzell number for that gasket is B-1104, also available from Tempest.

The correct lineup in my case is a Lycoming 72053 gasket against the mounting, then a LW-12347 plate, then a MS9144-01 or B-1104 gasket against the governor. Here is a diagram from the Mooney document listed below that shows it best.
i-PsPshM8-M.jpg
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  • 2 years later...
Bubblehead 10-22-2016 12:21 PM

Dual Mag engines and prop governor oil leak safety issue
  I have been researching oil leaks because I have been fighting one on my engine for a couple of months. I came across several accident reports for airplanes with "D" suffix engines that experienced loss of power, sometimes engine overspeed, and often complete destruction of the engine due to loss of oil between the prop governor and the governor mounting pad. This pertains to rear mounted governors.

My engine is a O-360-A1F6D converted to fuel injection so this concerned me. The problem arises because engines with dual magnetos need a spacer plate with gaskets on each side on the prop governor or the governor shaft will bottom out and hold the governor out just enough to allow for an oil leak. Sometimes minor, sometimes catastrophic.

If you have a dual mag engine make sure you have this plate and the 2 correct gaskets installed.

Confusion happens over the right installation parts because Hartzell's instructions don't show it, they only say these are general instructions and check your airframe and powerplant manuals. Cessna's orginal manuals for the Cardinal RG, where my engine came from, don't show the spacer plate but Cessna put out an update that has apparently not been noticed by a lot of A&P/AIs. The Lycoming parts manual for my engine does show the plate but does not show the governor in the same illustration so it does not tell you to add the second gasket. That is why 1438A (below) is so important. In 1438A it shows the plate and two-gasket arrangement but with the close off plate not the governor. The 2nd gasket in that diagram has to be replaced with a MS9144-01 gasket. The Hartzell number for that gasket is B-1104, also available from Tempest.

The correct lineup in my case is a Lycoming 72053 gasket against the mounting, then a LW-12347 plate, then a MS9144-01 or B-1104 gasket against the governor. Here is a diagram from the Mooney document listed below that shows it best.
i-PsPshM8-M.jpg


Piloto,
Great post! Question: can you see the spacer and gaskets with governor installed or do you have to remove governor? If so, does that require entire engine to come off? Thanks


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2 hours ago, RightRudder said:

Any final resolution to this original thread?   Many possibilities....  interested to hear outcome.

 

Unfortunately, the original poster never returned...

His post count remains at 1... and never checked back in...

Best regards,

-a-

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Well, FWIW, it looks just like my leak.  It's coming from the prop governor and is slated to get overhauled.  It collects on a little "shelf" right below and eventually runs down and drips on the tire and sprays down the belly.  The little "shelf" i believe is part of the nosewheel mount.

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First off, I'm a brand new airplane owner, 10 weeks now, 6 of those weeks my 62 M20C was down for a broken tach cable. I have a similar leak somewhere in my IO-360-A1D. The only mechanic on the field looked at it twice already and keeps telling me its venting out of the breather tube. I don't know exactly where I need to fill it up to before it wont blow out yet, but I've heard that if you fill it to 8 quarts you will dump at least two of them. I have tried 6 quarts, lost a quart on a three hour flight, tried starting at five quarts, lost about a half quart on a 2 hour flight. Then, to make things worse, the only mechanic on the field has moved out of state. Now I need to find another mechanic, hopefully he knows more about Mooney's and find this leak. I don't think its venting out a whole quart out of the breather tube, or am I wrong?

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Yes.  That oil consumption is not normal.

Is the belly dripping with oil from a leak, or are the plugs covered with oil due to oil going by the rings.  That amount of oil will leave a residue somewhere and that will be a clue.

If the airplane sat awhile before you bought it, the oil consumption may decrease the more you fly it, but generally oil consumption issues don't fix themselves.  If the plane sat for a long time...you might try some MMO (Marvel Mystety Oil), but that's a controversial subject on Mooneyspace.

For engine oil consumption issues, you don't need a Mooney specific mechanic.  It's an O-360, so any good engine mechanic can address your problem.

Your engine is talking to you.  Watch the signs.

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4 minutes ago, Mooneymite said:

Yes.  That oil consumption is not normal.

Is the belly dripping with oil from a leak, or are the plugs covered with oil due to oil going by the rings.  That amount of oil will leave a residue somewhere and that will be a clue.

If the airplane sat awhile before you bought it, the oil consumption may decrease the more you fly it, but generally oil consumption issues don't fix themselves.  If the plane sat for a long time...you might try some MMO (Marvel Mystety Oil), but that's a controversial subject on Mooneyspace.

For engine oil consumption issues, you don't need a Mooney specific mechanic.  It's an O-360, so any good engine mechanic can address your problem.

Your engine is talking to you.  Watch the signs.

Yeah I don't speak its language very well yet but I do know something is amiss. I haven't pulled the plugs yet. It was flown but not a lot before me according to the previous owner. I have put 30 hours on it in 6 weeks, so I am flying it relatively regularly. The belly of the cowling was coated pretty well, but like someone said earlier in this post, It looked like a murder scene, and it was sprayed all over the place, so no real clue there. I cleaned it up before the last time I flew, but came back to home airport very late at night and just didn't have the energy to investigate it further that night. My hangar is over an hour away from my place and I work 70-80 hours a week. Hell, I'm at work right now even!! 

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Mike Busch has a good article about tracing oil consumption.  It’s either leaking, coming into the cylinder(s) through the valves, or the piston rings aren’t working right (or are broken).  Those are basically the only 3 ways oil escapes.  Each leaves a different symptom. Plugs, belly, and exhaust pipe are areas to investigate for residue.  Do a compression check too...

Now I’m no mechanic, so the above is simplified, but that’s the gist.  Do some research before you take it to someone so you know roughly how they might diagnose it and what the symptoms they find might mean.  Example... lots of oil on the belly out the breather tube may mean you’ve got a problem with blowby, potentially your rings.  You’d probably want to do a compression check or boroscope to narrow down which cylinder.

Edited by Ragsf15e
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Thomas where are you located...

Lets See if we can help get you some help from somebody who knows...

A tach cable is an easy fix... and probably won’t make you land, now!

Running out of oil becomes a land now event...

If exhaust pressure is pushing all of your oil overboard, there is a test for that...

Is all of the lost oil going out the case vent?

Or are there other location of lost oil?

Any oil going out the exhaust pipe?

Any oil collecting on the lower plugs...

PP thoughts only, not a mechanic...

Best regards,

-a-

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  • 3 months later...
On ‎8‎/‎25‎/‎2019 at 9:31 PM, carusoam said:

Thomas where are you located...

Lets See if we can help get you some help from somebody who knows...

A tach cable is an easy fix... and probably won’t make you land, now!

Running out of oil becomes a land now event...

If exhaust pressure is pushing all of your oil overboard, there is a test for that...

Is all of the lost oil going out the case vent?

Or are there other location of lost oil?

Any oil going out the exhaust pipe?

Any oil collecting on the lower plugs...

PP thoughts only, not a mechanic...

Best regards,

-a-

Carusoam,

Sorry I didn't see this reply until today. I am located in Carlsbad, NM, my plane is in Hobbs, NM an hour away from me, I fly to Tucson, AZ as much as possible because that is where my wife is currently living. I have found a mechanic in Arizona so I am in the process of finding the leak or why its burning oil. I still have an oil screen, so that needs to be changed out as well, and finding time to get this looked at is nearly impossible for me. I work in the gas and oil business and work 70-80 hours a week. trying to study for my IFR rating at the same time and then trying to get this issue resolved has been a daunting task!!! thanks for the advice though. Now that I have put about 100 hours on the engine since I have had it, It doesn't seem to leak as much as it did before but it does still leak some.

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